Modifying the ISNO options with the chdev and ifconfig commands

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You can use the following commands to first verify system and interface support and then to set and verify the new values.

Make sure the use_isno option is enabled by using the following command:
```
# no -a | grep isno
use_isno = 1
```

Make sure the interface supports the five new ISNOs by using the lsattr -El command:

# lsattr -E -l en0 -H
attribute           value description                          user_settable
:
rfc1323             Enable/Disable TCP RFC 1323 Window Scaling True
tcp_mssdflt         Set TCP Maximum Segment Size               True
tcp_nodelay         Enable/Disable TCP_NODELAY Option          True
tcp_recvspace       Set Socket Buffer Space for Receiving      True
tcp_sendspace       Set Socket Buffer Space for Sending        True

Set the interface-specific values, using either the ifconfig or chdev command. The ifconfig command sets values temporarily (best used for testing). The chdev command alters the ODM, so custom values return after system reboots.
For example, to set the tcp_recvspace and tcp_sendspace to 64 KB and enable tcp_nodelay, use one of the following methods:
```
# ifconfig en0 tcp_recvspace 65536 tcp_sendspace 65536 tcp_nodelay 1
```
or
```
# chdev -l en0 -a tcp_recvspace=65536 -a tcp_sendspace=65536 -a tcp_nodelay=1
```

Verify the settings using the ifconfig or lsattr command:

# ifconfig en0
en0: flags=5e080863,c0<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST,GROUPRT,64BIT,CHECKSUM_OFFLOAD,PSEG,CHAIN>
        inet 9.19.161.100 netmask 0xffffff00 broadcast 9.19.161.255
        tcp_sendspace 65536 tcp_recvspace 65536 tcp_nodelay 1

# lsattr -El en0
rfc1323             Enable/Disable TCP RFC 1323 Window Scaling True
tcp_mssdflt         Set TCP Maximum Segment Size               True
tcp_nodelay   1     Enable/Disable TCP_NODELAY Option          True
tcp_recvspace 65536 Set Socket Buffer Space for Receiving      True
tcp_sendspace 65536 Set Socket Buffer Space for Sending        True